They are a couple of years old, but that things would have changed for the better in Russia does not sound likely, all reports are talking of the opposite.
There are also many reports about systematic rape in Russian prisons. Committed by inmates who are forced by the guards in exchange for less inhuman treatment.
Search for Nawalny's reports how is being treated if you still have not enough. Of course he gets carefully selected treatment because they know that the international press is reporting. But still it's a country where not only the leader is a brutal criminal.
Yes! Nobody can just claim such terrible acts from a state that openly murders political opponents and currently is carrying out an invasion of a peaceful country.
> Nothing stoping Russians from starting sabotage operations internally in protest.
A lot is stopping most people.
First you need somewhat objective information what is happening. A vast majority of the population does not have that. All independent voices have silenced, except if you are a political activist and know what to search for.
Then you need to take significant risk to commit crimes. As a small saboteur they won't have Novichok for you, but Russian prisons are very close to systematic
torture. Especially for prisoners with a political background.
Not only arrested. Beaten up and treated with electro shocks. Putin's Russia is not about humanity.